Image blur correction apparatus and optical apparatus

ABSTRACT

An image blur correction apparatus includes an shooting state detecting portion that determines a shooting state of a first shooting state or a second shooting state based on an angular velocity signal, and a controller that performs an image blur correction using characteristics depending on a determination result of the shooting state determining portion, and the shooting state determining portion determines that the first shooting state has started when the angular velocity signal exceeds a first threshold value and exceeds a second threshold value having an opposite sign of the first threshold value within a predetermined time after exceeding the first threshold value, and determines that the first shooting state is continuously maintained when the angular velocity signal exceeds a third threshold value and exceeds a fourth threshold value that has an opposite sign of the third threshold value within the predetermined time after exceeding the third threshold value.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image blur correction apparatus thatperforms an image blurring correction using characteristics depending ona shooting state.

2. Description of the Related Art

A previous image blur correction apparatus has a prism or a lens membercapable of displacing an optical axis that is disposed in an opticalpath of incident light into an image pickup element, and displacing theoptical axis in accordance with a hand shake so as to perform an imageblur correction. In the image blur correction apparatus, a correctableangle of the optical axis by a correction lens in a case where a zoomposition is located at a telephoto side is larger than that in a casewhere the zoom position is located at a wide-angle side. On conditionthat amounts of correction by the correction lens are equal to eachother, the correction angle by the correction lens at the telephoto sideis larger than that at the wide-angle side.

Japanese Patent Laid-Open No. 2010-139694 discloses a blur correctionapparatus that includes a vibration detector that detects a vibration soas to output its detected signal and that release the limit of a lensdriving range when the detected signal is larger than a predeterminedlevel so as to widen the lens driving range. The vibration detector ofJapanese Patent Laid-Open No. 2010-139694 determines that the detectedsignal is larger than the predetermined level using a ratio in which thedetected signal exceeds a certain threshold value or the number of timesby which the detected signal exceeds a certain threshold value in a unittime.

However, an amount of the hand shake is not always constant, and alsocharacteristics of the shake (vibration) are varied in accordance with auser. In particular, when a shooting state is a state of shooting whilewalking where a shooting is per formed while walking, the user oftentakes an image while confirming a shot image. In this case, some usersunconsciously behave so as to absorb the hand shake when the state ofshooting while walking is maintained for a while, and therefore theamount of the shake (image blur) may be temporarily reduced by thebehavior. Accordingly, when the determination is performed only by usingthe amount of the shake (the image blur), there is a case in which theimage blur correction in the state of shooting while walking is stoppedin spite of the state of shooting while walking, and it is difficult toperform the image blur correction with high accuracy.

SUMMARY OF THE INVENTION

The present invention provides an image blur correction apparatus thatperforms an image blurring correction using characteristics depending ona shooting state so as to improve detection accuracy of the shootingstate. The present invention also provides an optical apparatus that hasthe image blur correction apparatus.

An image blur correction apparatus as one aspect of the presentinvention includes an shooting state detecting portion configured todetermine a shooting state of one of a first shooting state and a secondshooting state based on an angular velocity signal, and a controllerconfigured to perform an image blur correction using characteristicsdepending on a determination result of the shooting state determiningportion. The shooting state determining portion determines that thefirst shooting state has started when the angular velocity signalexceeds a first threshold value and exceeds a second threshold valuehaving an opposite sign of the first threshold value within apredetermined time after exceeding the first threshold value, determinesthat the first shooting state is continuously maintained when theangular velocity signal exceeds a third threshold value smaller than thefirst threshold value and exceeds a fourth threshold value that has anopposite sign of the third threshold value and that is smaller than thesecond threshold value within the predetermined time after exceeding thethird threshold value on condition that the shooting state is the firstshooting state, and determines that the first shooting state has endedwhen the angular velocity signal does not exceed the third thresholdvalue, or does not exceed the fourth threshold value within thepredetermined time after exceeding the third threshold value oncondition that the shooting state is the first shooting state.

An image blur correction apparatus as another aspect of the presentinvention includes an shooting state detecting portion configured todetermine a shooting state of one of a first shooting state and a secondshooting state based on an angular velocity signal, and a controllerconfigured to perform an image blur correction using characteristicsdepending on a determination result of the shooting state determiningportion. The shooting state determining portion determines that thefirst shooting state has started when the angular velocity signalexceeds a first threshold value and exceeds a second threshold valuehaving an opposite sign of the first threshold value within a first timeafter exceeding the first threshold value, determines that the firstshooting state is continuously maintained when the angular velocitysignal exceeds a third threshold value and exceeds a fourth thresholdvalue that has an opposite sign of the third threshold value within asecond time longer than the first time after exceeding the thirdthreshold value on condition that the shooting state is the firstshooting state, and determines that the first shooting state has endedwhen the angular velocity signal does not exceed the third thresholdvalue, or does not exceed the fourth threshold value within the secondtime after exceeding the third threshold value on condition that theshooting state is the first shooting state.

An optical apparatus as another aspect of the present invention includesthe image blur correction apparatus.

Further features and aspects of the present invention will becomeapparent from the following description of exemplary embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an image pickup apparatus (an opticalapparatus) that includes an image blur correction apparatus in thepresent embodiment.

FIGS. 2A and 2B are diagrams of illustrating integral characteristics ofthe image blur correction apparatus in the present embodiment.

FIG. 3 is a flowchart of illustrating an operation of a shooting statedetermining portion in the present embodiment.

FIG. 4 is a flowchart of determining start of shooting while walking inthe first embodiment.

FIG. 5 is a flowchart of determining end of shooting while walking inthe first embodiment.

FIG. 6 is a vibration detection result as a comparative example withrespect to the first embodiment.

FIG. 7 is a vibration detection result in the first embodiment.

FIG. 8 is a flowchart of determining start of shooting while walking inthe second embodiment.

FIG. 9 is a flowchart of determining end of shooting while walking inthe second embodiment.

FIG. 10 is a vibration detection result in the second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention will be described belowwith reference to the accompanied drawings. In each of the drawings, thesame elements will be denoted by the same reference numerals and theduplicate descriptions thereof will be omitted.

First Embodiment

First of all, a configuration of an image blur correction apparatus in afirst embodiment of the present invention will be described. FIG. 1 is ablock diagram of an image pickup apparatus 100 (an optical apparatussuch as a camera or a video camera) that includes an image blurcorrection apparatus 13 in the present embodiment. The image pickupapparatus 100 can perform an image blur correction by moving a shiftlens for correcting a hand shake in a direction orthogonal to an opticalaxis OA (an orthogonal direction of the optical axis).

Reference numeral 10 denotes a lens unit (a lens barrel) that has aconfiguration of an inner focus type. The lens unit 10 is configured byincluding a zoom lens 101, a stop 102, a shift lens 103, and a focuslens 104. Light passing through the lens unit 10 is imaged on an imagepickup element 11 such as a CCD or a CMOS. The lens unit 10 has theconfiguration of the inner focus type, but the present embodiment is notlimited to this and can also be applied to a lens unit which has aconfiguration of a rear focus type. In addition, the present embodimentcan be applied to both cases where the image pickup apparatus 100 isintegrally configured by the lens unit 10 and an image pickup apparatusbody (a camera body) and the lens unit 10 is configured so as to beinterchangeable with respect to the image pickup apparatus body.

Reference numeral 12 denotes a gyro sensor (an image blur detectionsensor) that detects an angular velocity signal (an image blur) of theimage pickup apparatus 100. The gyro sensor 12 is configured byincluding a yaw direction gyro sensor 121 that detects an angularvelocity signal in a yaw direction and a pitch direction gyro sensor 122that detects an angular velocity signal in a pitch direction. However,the present embodiment is not limited to this, and one gyro sensor thatis capable of detecting angular velocity signals in two-axis orthree-axis directions may also be used.

Reference numeral 13 denotes an image blur correction apparatus. Theimage blur correction apparatus 13 is configured by including an A/Dconverter 131, a high-pass filter 132 (HPF), an integral filter 133, alens controller 134 (a controller), and an integral characteristicswitching portion 135. The image blur correction apparatus 13 performs apredetermined processing for an angular velocity signal that is detectedby the gyro sensor 12 so as to generate a signal for driving the shiftlens 103 in the direction orthogonal to the optical axis. In the presentembodiment, the image blur correction apparatus 13 drives the shift lens103, but the present embodiment is not limited to this and it can alsobe configured so as to drive the image pickup element 11 in thedirection orthogonal to the optical axis.

Reference numeral 14 denotes a switch portion. The switch portion 14 isoperated so that whether the image blur correction is performed or not(on/off of an image stabilization function) can be selected. The switchportion 14 is not limited to a switch portion which selects whether theimage blur correction is performed or not, and it may also be configuredso that the control of the image blur correction is changed by switchingthe switch portion 14.

Next, a flow of a signal processing that is performed by the image blurcorrection apparatus 13 will be described. First of all, the angularvelocity signal (an analog signal) that is obtained by the gyro sensor12 is converted into a digital signal by the A/D converter 131.Subsequently, the digitalized angular velocity signal passes through thehigh-pass filter 132 so as to obtain an angular velocity signal in whichDC components (low frequency components) have been cut.

The integral characteristic switching portion 135 is configured byincluding a shooting state determining portion 135 a (a shooting statedetermining unit), an integral characteristic determining portion 135 b,and an integral characteristic data group 135 c. The shooting statedetermining portion 135 a recognizes amplitude or a frequency of thevibration (the hand shake) or the like based on the angular velocitysignal that has passed the high-pass filter 132 so as to determine acurrent shooting state. In the present embodiment, the shooting statedetermining portion 135 a determines whether the state is a state ofshooting while walking (a first shooting state) or a state of shootingat rest (a second shooting state), but the present embodiment is notlimited to this. For example, a state of shooting on a vehicle may beset as a first shooting state, and another shooting state can also bearbitrarily added.

The integral characteristic determining portion 135 b determinesintegral characteristics that are applied to the integral filter 133 inaccordance with a determination result of the shooting state determiningportion 135 a. The integral characteristic switching portion 135 storesthe integral characteristic data group 135 c that has a plurality ofintegral characteristics (integral characteristics 1, 2, . . . , n) sothat a specific integral characteristic is selected from among theintegral characteristics of the integral characteristic data group 135c.

When the integral characteristic suitable for the current shooting stateis selected by the integral characteristic switching portion 135, theangular velocity signal passes through the integral filter 133 to whichits integral characteristic is applied so as to be changed to an angulardisplacement signal. The lens controller 134 uses the angulardisplacement signal obtained by passing through the integral filter 133so as to move the shift lens 103 in the yaw direction and the pitchdirection that are the directions orthogonal to the optical axis, in adirection opposite to a moving direction of the image pickup apparatus100 caused by the vibration (the hand shake). In other words, the lenscontroller 134 performs the image blur correction using thecharacteristics (the integral characteristics) depending on thedetermination result obtained by the shooting state determining portion135 a. Thus, since the image blur correction apparatus 13 of the presentembodiment includes the integral characteristic switching portion 135,it can determine the current shooting state so as to perform the imageblur correction control which is suitable for its shooting state.

Next, how the drive of the shift lens 103 is changed in accordance withthe integral characteristics will be described. FIGS. 2A and 2B arediagrams of illustrating the integral characteristics of the image blurcorrection apparatus 13 in the present embodiment, and FIGS. 2A and 2Billustrate first integral characteristics (a state of shooting whilewalking) and second integral characteristics (a state of shooting atrest), respectively.

Both the first integral characteristics and the second integralcharacteristics are integral characteristics that have a minimum cutofffrequency fc1 and a maximum cutoff frequency fc2. In the first integralcharacteristics, the cutoff frequency is gradually heightened when avibration angular displacement that represents the extent of thevibration exceeds D3, and the cutoff frequency reaches the maximumcutoff frequency fc2 when the vibration angular displacement is D4. Onthe other hand, in the second integral characteristics, the cutofffrequency is gradually heightened when the vibration angulardisplacement exceeds D1, and the cutoff frequency reaches the maximumcutoff frequency fc2 when the vibration angular displacement is D2. Inother words, the second integral characteristics are integralcharacteristics that enlarge a lens centripetal force (narrow an imageblur correction range) even for a small vibration (a small hand shake)such as a vibration angular displacement D2. On the other hand, thefirst integral characteristics are integral characteristics that reducethe lens centripetal force (widen the image blur correction range) forthe small vibration.

The lens centripetal force means a force that sends the shift lens 103to a center of the optical axis with respect to the vibration. In otherwords, when a lens driving limit range on a mechanical stroke isconstant, the lens driving range (the image blur correction range) iswidened as the lens centripetal force is decreased. As illustrated inFIGS. 2A and 2B, the second integral characteristics are characteristicsin which the cutoff frequency (the lens centripetal force) is high(strong) even in a small vibration angular displacement. In other words,it is integral characteristics that have a narrow lens driving range. Onthe other hand, the first integral characteristics are characteristicsin which the cutoff frequency (the lens centripetal force) is low (weak)up to a large vibration angular displacement. In other words, it isintegral characteristics that have a wide lens driving range so as tocorrect a large amount of image blur.

Thus, in the present embodiment, a plurality of different integralcharacteristics are previously stored and the integral characteristicsare switched in accordance with the shooting state, i.e. thecharacteristics are switched so as to widen the range of the image blurcorrection in the first shooting state compared to the second shootingstate, so as to change the lens driving range. For example, when it isdetermined that a current shooting state is the state of shooting whilewalking (the first shooting state), the integral characteristicswitching portion 135 is set so as to select the first integralcharacteristics of FIG. 2A. On the other hand, when it is determinedthat the current shooting state is the state of shooting at rest (thesecond shooting state), the integral characteristic switching portion135 is set so as to select the second integral characteristics of FIG.2B. In such a configuration, the lens driving range (the image blurcorrection range) during shooting while walking is wider than thatduring shooting at rest, and therefore a large amount of image blur thatis generated during shooting while walking can also be corrected. As aresult, an image blur correction which is suitable for the currentshooting state can be performed.

In the present embodiment, the image blur correction control that setsdifferent integral characteristics in accordance with the shooting stateso as to change the lens driving range is described, but the image blurcorrection control is not limited to a configuration in which theintegral characteristics are changed. For example, when it is determinedthat the current shooting state is during panning or tilting, it mayalso be changed so as to perform a control independent of the integralcharacteristics such as fixing the lens at a center position of theoptical axis.

Next, referring to FIG. 3, the operation of the shooting statedetermining portion 135 a in the present embodiment is described. FIG. 3is a flowchart of illustrating the operation of the shooting statedetermining portion 135 a in the present embodiment. The shooting statedetermining portion 135 a determines the shooting state using theangular velocity signal that is obtained by passing through thehigh-pass filter 132. The angular velocity signal after passing throughthe high-pass filter 132 is used because an offset component caused by ahand shake, i.e. the offset component close to the DC component, needsto be removed. According to such a configuration, a higher accuracyshooting state determination can be performed.

When the shooting state determination is started by the shooting statedetermining portion 135 a in Step S301 of FIG. 3, first of all in Step302, the determination whether the shooting while walking is started ornot is performed. When the shooting state determining portion 135 adetermines that the current shooting state is the state of shootingwhile walking, it selects the first integral characteristics in StepS303 so as to widen the lens driving range. Then, it continuouslymaintains the state in which the lens driving range is widened (thestate in which the first integral characteristics are selected) whiledetermining the state of shooting while walking. Then, in Step S304, theshooting state determining portion 135 a determines whether the state ofshooting while walking has ended. When it is determined that the stateof shooting while walking is ended in Step S304, the flow returns toStep S302, and a determination of start of shooting while walking isperformed.

When it is determined that the shooting while walking is not started inStep S302, the flow proceeds to Step S305. In Step S305, the shootingstate determining portion 135 a determines whether a panning isperformed or not. When it is determined that the panning is performed,the flow proceeds to Step S306 and the panning control is performed. Onthe other hand, when the shooting state determining portion 135 adetermines that the panning is not performed in Step S305, the flowproceeds to Step S307 and it determines that the current shooting stateis a state of shooting at rest. In this case, the second integralcharacteristics are selected so as to perform the image blur correctionwithin the narrow lens driving range.

Next, referring to FIG. 4, a determination of start of shooting whilewalking in the present embodiment is described in detail. FIG. 4 is aflowchart of the determination of start of shooting while walking in thepresent embodiment. The determination of start of shooting while walkingillustrated in FIG. 4 corresponds to Step S302 in FIG. 3, which isperformed by the shooting state determining portion 135 a.

When the determination of start of shooting while walking is started inStep S401, it is determined whether the angular velocity signal exceedsa first threshold value (an absolute value) or not in Step S402. Thisdetermination process is repeated until the angular velocity signalexceeds the first threshold value. When it is determined that theangular velocity signal exceeds the first threshold value, a count resetand a count up are performed in Steps S403 and S404, respectively.Subsequently, it is determined whether the count is within apredetermined count threshold value (within a predetermined time afterthe signal exceeds the first threshold value) in Step S405. When thecount is within the predetermined count threshold value, the flowproceeds to Step S406.

In Step S406, whether the angular velocity signal exceeds a secondthreshold value (an absolute value) that has an opposite sign of thefirst threshold value is determined. The absolute values of the firstthreshold value and the second threshold value may be equal to eachother, or alternatively they may be different from each other. When theangular velocity signal does not exceed the second threshold value (theabsolute value) in Step S406, a loop of Steps S404, S405, and S406 isrepeated. On the other hand, the angular velocity signal exceeds thesecond threshold value in Step S406, it is determined that the currentshooting state is the state of shooting while walking in Step S407. Whenthe count exceeds a predetermined count threshold value during the loopof Steps S404 to S406 (in Step S405), the flow returns to Step S402.

Next, referring to FIG. 5, a determination of end of shooting whilewalking in the present embodiment is described in detail. FIG. 5 is aflowchart of the determination of end of shooting while walking in thepresent embodiment. The determination of end of shooting while walkingillustrated in FIG. 5 corresponds to Step S304 of FIG. 3, which isperformed by the shooting state determining portion 135 a.

In the state of shooting while walking, when the determination of end ofshooting while walking is started in Step S501, it is determined whetherthe angular velocity signal exceeds a third threshold value in StepS502. In the present embodiment, the third threshold value (the absolutevalue) is set so as to be smaller than the first threshold value (theabsolute value) that is used for the determination of start of shootingwhile walking. This determination process is repeated (Y in Step S502)until the angular velocity signal does not exceed the third thresholdvalue (N in Step S502). When the angular velocity signal does not exceedthe third threshold value, the flow proceeds to Step S503, where thecount reset and the count up are performed in Steps S503 and S504,respectively. Subsequently, it is determined whether the count is notless than a predetermined count threshold value (not less than a firstpredetermined time ΔT after the angular velocity signal exceeds thethird threshold value) in Step S505.

When the count is within the predetermined threshold value (within thepredetermined time after the signal exceeds the third threshold value)in Step S505, a loop of Steps S507, S504, and S505 is repeated until theangular velocity signal is determined to exceed a fourth threshold value(an absolute value) of an opposite sign of the third threshold value inStep S507. On the other hand, when the count is not less than thepredetermined threshold value in Step S505, the flow proceeds to StepS506, where it is determined that the shooting while walking has ended.When it is determined that the angular velocity signal exceeds thefourth threshold value (an absolute value) of an opposite sign of thethird threshold value in Step S507 during the loop of Steps S507, S504,and S505, the flow returns to Step S502. In the present embodiment, thefourth threshold value (the absolute value) is set to be smaller thanthe second threshold value (the absolute value). The absolute values ofthe third threshold value and the fourth threshold value may be equal toeach other, or alternatively they may be different from each other.

As described above, using the flows described with reference to FIGS. 4and 5, the start of shooting while walking and the end of shooting whilewalking can be determined with high accuracy. In the present embodiment,a determination reference of the end of shooting while walking is setmore strictly than a determination reference of the start of shootingwhile walking. Therefore, even when a user unconsciously behaves so asto absorb the hand shake, the determination of shooting while walking isnot easily removed and a high accuracy control can be performed.

Next, referring to FIG. 6, a vibration detection result in a case wherethe threshold values of the angular velocity signal that are used forthe determinations of the start of shooting while walking and the end ofshooting while walking are set to be a value equal to each other will bedescribed. FIG. 6 is the vibration detection result as a comparativeexample with respect to the present embodiment. This comparative exampleis a detection result in a case where the behavior of absorbing the handshake that is unconsciously performed by the user does not care (in acase where the present embodiment is not applied). A waveformillustrated in FIG. 6 is a waveform that indicates an angular velocitysignal in the state of shooting at rest (a common hand shake) to move tothe state of shooting while walking, and then to return to the state ofshooting at rest. The first threshold value, the second threshold value,and a time threshold value (the predetermined time) of the angularvelocity signal is indicated as V1, −V1, and ΔT, respectively, and FIG.6 also indicates the determined shooting state under the waveform.

When viewing the waveform in accordance with the flow of the time, firstof all, a vibration not less than the first threshold value V1 isdetected at the time T1, and a vibration not more than the secondthreshold value −V1 (not less than the threshold value of the secondthreshold value) is detected at the time T2. Since the time period fromthe time T1 to the time T2 is within the time threshold value ΔT, it isdetermined that the state is in shooting while walking. However, sincethe user unconsciously behaves so as to absorb the hand shake (thevibration), then the amplitude of the shake is temporarily decreased.Therefore, after the vibration not more than the second threshold value−V1 (not less than the absolute value of the second threshold value) atthe time T3, a vibration not less than the first threshold value V1cannot be detected by a time T4 that is within the time threshold valueΔT, and therefore it is erroneously determined that the state is inshooting at rest in spite of the shooting at rest. Then, a condition ofdetermining the start of shooting while walking is met at a time T5 andtherefore it is determined that the state is in shooting while walkingagain, but the image blur correction control in shooting while walkingcannot be performed during the time T4 to time T5. Therefore, there ishigh possibility that a large amount of blur (shake) is generated on ascreen.

Next, referring to FIG. 7, the a vibration detection result in a casewhere the threshold values (the third threshold value and the fourththreshold value) of the angular velocity signal that are used for thedetermination of the end of shooting while walking are smaller than thethreshold values (the first threshold value and the second thresholdvalue) of the angular velocity signal that are used for thedetermination of the start of shooting while walking will be described.FIG. 7 is a vibration detection result in the present embodiment. Awaveform illustrated in FIG. 7 is the same as the waveform illustratedin FIG. 6. The first threshold value and the second threshold value thatare used for the determination of the start of shooting while walkingare indicated as V1 and −V1 respectively, the third threshold value andthe fourth threshold value that are used for the determination of theend of shooting while walking are indicated as V2 and −V2 respectively,and the time threshold value (the predetermined time) is indicated asΔT. In FIG. 7, the determined shooting state is indicated under thewaveform.

First of all, a vibration which is not less than the first thresholdvalue V1 is detected at the time T1, and then a vibration which is notmore than the second threshold value −V1 (not less than the absolutevalue of the second threshold value) having an opposite sign is detectedat the time T2. Since the time period from the time T1 to the time T2 iswithin the time threshold value ΔT, it is determined that the state isin shooting while walking. Then, as described with reference to FIG. 6,the amplitude of the vibration is temporarily reduced by the unconsciousbehavior of the user. However, in the present embodiment, the thirdthreshold value V2 is set to be a value smaller than the first thresholdvalue V1. Therefore, a vibration that is not less than the thirdthreshold value V2 can be detected at the time T6, and it iscontinuously determined that the state is in shooting while walking evenwhen the amount of the vibration is reduced. Thus, according to thedetermination method of the present embodiment, an image blur correctioncontrol in shooting while walking can be continuously maintained withhigh accuracy even when the user unconsciously behaves so as to absorbthe hand shake.

In the present embodiment, the shooting state determining portion 135 adetermines that the first shooting state has started when the angularvelocity exceeds the first threshold value and also it exceeds thesecond threshold value that has an opposite sign of the first thresholdvalue within the predetermined time after it exceeds the first thresholdvalue. Furthermore, the shooting state determining portion 135 adetermines that the first shooting state is continuously maintained whenthe angular velocity signal exceeds the third threshold value that issmaller than the first threshold value and also it exceeds the fourththreshold value that has an opposite sign of the third threshold valueand that is smaller than the second value within the predetermined timeafter it exceeds the third threshold value on condition that theshooting state is the first shooting state. On the other hand, theshooting state determining portion 135 a determines that the firstshooting state is ended when the angular velocity signal does not exceedthe third threshold value or it does not exceed the fourth thresholdvalue within the predetermined time after it exceeds the third thresholdvalue on condition that the shooting state is the first shooting state.

As described above, according to the present embodiment, the shootingstate can be recognized with high accuracy and an image blur correctioncontrol that is optimized for each of the shooting states can beperformed. In particular, even when a user unconsciously behaves so asto absorb a hand shake in shooting while walking, the determinations ofthe start of shooting while waking and the end of shooting while walkingcan be continuously performed.

Second Embodiment

Next, an image blur correction apparatus in a second embodiment of thepresent invention will be described. The present embodiment is differentfrom the first embodiment only in the methods of determining the startof shooting while walking and the end of shooting while walking by theshooting state determining portion 135 a. Other configurations of thepresent embodiment are similar to those of the first embodiment, andtherefore, descriptions thereof are omitted.

First of all, referring to FIG. 8, a flow of determining the start ofshooting while walking in the present embodiment is described in detail.FIG. 8 is a flowchart of the determination of the start of shootingwhile walking in the present embodiment. The determination of the startof shooting while walking illustrated in FIG. 8 corresponds to Step S302of FIG. 3, which is performed by the shooting state determining portion135 a.

When the determination of the start of shooting while walking is startedin Step S801, it is determined whether the angular velocity signalexceeds the first threshold value (the absolute value) in Step S802.This determination process is repeated until the angular velocity signalexceeds the first threshold value. When it is determined that theangular velocity signal exceeds the first threshold value, the countreset and the count up are performed in Steps S803 and S804,respectively. Subsequently, it is determined whether the count is withinthe first count threshold value (within the first time after the angularvelocity signal exceeds the first threshold value) in Step S805. Whenthe count is within the first count threshold value, the flow proceedsto Step S806.

In Step S806, it is determined whether the angular velocity signalexceeds the second threshold value (the absolute value) that has anopposite sign of the first threshold value. The absolute values of thefirst threshold value and the second threshold value may be equal toeach other, or alternatively they may be different from each other. Whenthe angular velocity signal does not exceed the second threshold value(the absolute value) in Step S806, a loop of Steps S804, S805, and S806is repeated. On the other hand, the angular velocity signal exceeds thesecond threshold value in Step S806, it is determined that the currentshooting state is the state of shooting while walking in Step S807. Whenthe count exceeds the first count threshold value during the loop ofSteps S804 to S806 (in Step S805), the flow returns to Step S802.

Next, referring to FIG. 9, a flow of determining the end of shootingwhile walking in the present embodiment is described in detail. FIG. 9is a flowchart of the determination of end of shooting while walking inthe present embodiment. The determination of end of shooting whilewalking illustrated in FIG. 9 corresponds to Step S304 of FIG. 3, whichis performed by the shooting state determining portion 135 a.

In the state of shooting while walking, when the determination of theend of shooting while walking is started in Step S901, it is determinedwhether the angular velocity signal exceeds the third threshold value inStep S902. In the present embodiment, the third threshold value (theabsolute value) is a value equal to the first threshold value (theabsolute value) that is used for the determination of the start ofshooting while walking, or alternatively the third threshold value maybe set to a value smaller than the first threshold value. Thisdetermination process is repeated (Y in Step S902) until the angularvelocity signal does not exceed the third threshold value (N in StepS902). When the angular velocity signal does not exceed the thirdthreshold value, the flow proceeds to Step S903, where the count resetand the count up are performed in Steps S903 and S904, respectively.Subsequently, it is determined whether the count is not less than asecond count threshold value (not less than a second predetermined time2ΔT after the angular velocity signal does not exceed the thirdthreshold value) in Step S905. In the present embodiment, the secondpredetermined time is set to be a time that is longer than the firstpredetermined time.

When the count is within the second count threshold value (within thesecond predetermined time after the angular velocity signal exceeds thethird threshold value) in Step S905, a loop of Steps S907, S904, andS905 is repeated until the angular velocity signal is determined toexceed a fourth threshold value (an absolute value) of an opposite signof the third threshold value in Step S907. On the other hand, when thecount is not less than the second count threshold value in Step S905,the flow proceeds to Step S906, where it is determined that the shootingwhile walking is ended. When it is determined that the angular velocitysignal exceeds the fourth threshold value (the absolute value) of anopposite sign of the third threshold value in Step S907 during the loopof Steps S907, S904, and S905, the flow returns to Step S902. In thepresent embodiment, the fourth threshold value is set to be a valueequal to the second threshold value, but the present embodiment is notlimited to this and the fourth threshold value may also be set to avalue that is smaller than the second threshold value. The absolutevalues of the third threshold value and the fourth threshold value maybe equal to each other, or alternatively they may be different from eachother.

As described above, using the flows described with reference to FIGS. 8and 9, the start of shooting while walking and the end of shooting whilewalking can be determined with high accuracy. In the present embodiment,a determination reference of the end of shooting while walking is setmore strictly than a determination reference of the start of shootingwhile walking. Therefore, even when a user unconsciously behaves so asto absorb the hand shake, the determination of shooting while walking isnot easily removed and a high accuracy control can be performed.

Next, referring to FIG. 10, in the present embodiment, a vibrationdetection result in a case where the time threshold value used for thedetermination of the end of shooting while walking is set to be longerthan the time threshold value used for the determination of the start ofshooting while walking will be described. FIG. 10 is a vibrationdetection result in the present embodiment. In FIG. 10, the second countthreshold value (the second time) is set to be twice as large as thefirst count threshold value (the first time). However, the presentembodiment is not limited to this, and it is enough that the secondcount threshold value is set to be larger than the first count thresholdvalue (the second time is set to be longer than the first time). Thewaveform illustrated in FIG. 10 is the same as the waveform of FIGS. 6and 7.

First of all, a vibration of the angular velocity signal which is notless than the first threshold value V1 is detected at the time T1, and avibration which is not more than the second threshold value −V1 (notless than the absolute value of the second threshold value) is detectedat the time T2. Then, the amplitude of the vibration is decreased by theunconscious behavior of the user, and for a while after detecting thevibration which is not more than the third threshold value −V1 (not lessthan the absolute value of the third threshold value) at the time T3, avibration not less than the fourth threshold value V1 is not detected.In the present embodiment, however, the second time threshold value 2ΔT(the second time) used for the determination of the end of shootingwhile walking is set to be longer than the first time threshold value ΔT(the first time) used for the determination of the start of shootingwhile walking. Therefore, the vibration not less than the fourththreshold value V1 can be detected at the time T7 which is within thesecond time threshold value 2ΔT from the time T3, and the determinationof shooting while walking is continuously maintained even when theamount of the vibration is reduced. In other words, adopting thedetection method of the present embodiment, an image blur correctioncontrol in shooting while walking can be continuously performed evenwhen the user unconsciously behaves so as to absorb the hand shake.

In the present embodiment, the shooting state determining portion 135 adetermines that the first shooting state has started when the angularvelocity exceeds the first threshold value and also it exceeds thesecond threshold value that has an opposite sign of the first thresholdvalue within the first time after it exceeds the first threshold value.Furthermore, the shooting state determining portion 135 a determinesthat the first shooting state is continuously maintained when theangular velocity signal exceeds the third threshold value and also itexceeds the fourth threshold value that has an opposite sign of thethird threshold value within the second time that is longer than thefirst time after the angular velocity signal exceeds the third thresholdvalue on condition that the shooting state is the first shooting state.On the other hand, the shooting state determining portion 135 adetermines that the first shooting state is ended when the angularvelocity signal does not exceed the third threshold value or it does notexceed the fourth threshold value within the second time after itexceeds the third threshold value on condition that the shooting stateis the first shooting state.

As described above, according to the present embodiment, the shootingstate can be recognized with high accuracy and an image blur correctioncontrol that is optimized for each of the shooting states can beperformed. In particular, even when a user unconsciously behaves so asto absorb a hand shake in shooting while walking, the determinations ofthe start of shooting while waking and the end of shooting while walkingcan be continuously performed.

Each of the above embodiments is described on the assumption that thefirst shooting state is the state of shooting while walking, but is notlimited to this. For example, each of the above embodiments can also beapplied to a case where the first shooting state is a state of shootingon a vehicle. The determinations of the start and the end of the stateof shooting while walking in each of the above embodiments may also usea time period from a time at which the angular velocity signal exceeds athreshold value more than once to a time at which it exceeds a thresholdvalue having an opposite sign within a predetermined time. In suchdetermination, a time from a peak of the angular velocity signal to apeak of the angular velocity signal having an opposite sign can also beused.

Using the integral characteristics that enlarge the lens driving rangein shooting while walking, a large amount of the vibration (the imageblur) in shooting while walking can also be sufficiently corrected, andfurthermore the deterioration of the optical performance or the feelingof strangeness at the time of switching the control can be reduced sincethe lens driving range is not widened except for shooting while walking.

The angular velocity signal after passing through the high-pass filteris used for the determination of shooting state, but the presentembodiment is not limited to this and another signal may also be used ifit is a signal that represents the characteristics of the vibration. Forexample, angular velocity information before passing through thehigh-pass filter or angular displacement information after passingthrough the integral filter may also be used to determine the shootingstate.

With regard to the determination of the start of shooting while walkingand the determination of the end of shooting while walking, thethreshold values of the angular velocity signal for both thedeterminations are different from each other in the first embodiment,and the time threshold values for both the determinations are differentfrom each other in the second embodiment, and the determination accuracycan be improved if these are combined so as to perform thedetermination.

In the present embodiment, as characteristics of changing in order toenlarge the correction range (characteristics depending on thedetermination result of the shooting state determining portion), theintegral characteristics of the integral filter are used, but thepresent embodiment is not limited to this. For example, as thecharacteristics, a maximum value of an angular signal (the angularvelocity signal) may also be used. Alternatively, a maximum value of amoving amount signal by which a lens is actually driven, which isgenerated based on the angular signal, can also be used.

As described above, in the present embodiment, a threshold value usedfor determining the start of shooting while walking is set to be largerthan a threshold value used for determining the end of shooting whilewalking. Therefore, a determination requirement of the end of shootingwhile walking is stricter than a determination requirement of the startof shooting while walking. Therefore, according to each of the aboveembodiments, in an image blur correction apparatus that performs animage blur correction using characteristics depending on a shootingstate, the image blur correction apparatus that improves detectionaccuracy of the shooting state can be provided. An optical apparatusthat includes the image blur correction apparatus can also be provided.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2011-225422, filed on Oct. 13, 2011, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image blur correction apparatus comprising: asensor configured to detect an angular velocity signal; a controllerconfigured to execute: a shooting state determining task that determinesa shooting state of one of a first shooting state or a second shootingstate based on the angular velocity signal; an image blur correctiontask that performs an image blur correction using characteristicsdepending on a determination result of the shooting state determiningtask; a threshold task that determines a state of the angular velocitysignal in relation to a first positive threshold value, a secondnegative threshold value, a third negative threshold value, and a fourthpositive threshold value; a first shooting start state determining taskthat determines that the first shooting state has started: when thethreshold task determines, within a first predetermined period after thethreshold task determines that the angular velocity signal exceeds thefirst positive threshold value, that the angular velocity signal fallsbelow the second negative threshold value; and a first shooting endstate determining task that determines, while in the first shootingstate, that the first shooting state has ended: when the threshold taskdetermines that the angular velocity signal does not exceed the fourthpositive threshold value for an entire time during a secondpredetermined period after the threshold task determines that theangular velocity signal falls below the third negative threshold value,wherein the second predetermined period is longer than the firstpredetermined period.
 2. The image blur correction apparatus accordingto claim 1, wherein the image blur correction task performs the imageblur correction using the characteristics in the second shooting statewhen the first shooting end state determining task determines that thefirst shooting state has ended.
 3. The image blur correction apparatusaccording to claim 1, further comprising: an integral filter configuredto convert the angular velocity signal into an angular displacementsignal, wherein the characteristics are integral characteristics of theintegral filter, and wherein the integral characteristics are switchedso as to widen a range of the image blur correction in the firstshooting state compared to the second shooting state.
 4. The image blurcorrection apparatus according to claim 1, wherein the first shootingstate is a state of shooting while walking, and the second shootingstate is a state of shooting at rest.
 5. The image blur correctionapparatus according to claim 1, wherein the first shooting state is astate of shooting on a vehicle, and the second shooting state is a stateof shooting at rest.
 6. An optical apparatus comprising: an image blurcorrection apparatus; and an image stabilizing lens configured to bedriven by the image blur correction apparatus, wherein the image blurcorrection apparatus comprises: a sensor configured to detect an angularvelocity signal; a controller configured to execute: a shooting statedetermining task that determines a shooting state of one of a firstshooting state or a second shooting state based on the angular velocitysignal; an image blur correction task that performs an image blurcorrection using characteristics depending on a determination result ofthe shooting state determining task; a threshold task that determines astate of the angular velocity signal in relation to a first positivethreshold value, a second negative threshold value, a third negativethreshold value, and a fourth positive threshold value; a first shootingstart state determining task that determines that the first shootingstate has started: when the threshold task determines, within a firstpredetermined period after the threshold task determines that theangular velocity signal exceeds the first positive threshold value, thatthe angular velocity signal falls below second negative threshold value;and a first shooting end state determining task that determines, whilein the first shooting state, that the first shooting state has ended:after the threshold task determines that the angular velocity signalfalls below the third negative threshold value, when the threshold taskdetermines that the angular velocity signal does not exceed the fourthpositive threshold value having for an entire time during a secondpredetermined period after the threshold task determines that theangular velocity signal falls below the third negative threshold value,wherein the second predetermined period is longer than the firstpredetermined period.
 7. An image blur correction method comprising: ashooting state determining step of determining a shooting state of oneof a first shooting state or a second shooting state based on an angularvelocity signal detected using a sensor; an image blur correction stepof performing an image blur correction using characteristics dependingon a determination result of the shooting state determining step; athreshold step of determining a state of the angular velocity signal inrelation to a first positive threshold value, a second negativethreshold value, a third negative threshold value, and a fourth positivethreshold value; a first shooting start state determining step ofdetermining that the first shooting state has started: when thethreshold step determines, within a first predetermined period after thethreshold step determines that the angular velocity signal exceeds thefirst positive threshold value, that the angular velocity signal fallsbelow the second negative threshold value; and a first shooting endstate determining step of determining, while in the first shootingstate, that the first shooting state has ended: when the threshold stepdetermines that the angular velocity signal does not exceed the fourthpositive threshold value for an entire time during a secondpredetermined period after the threshold step determines that theangular velocity signal falls below the third negative threshold value,wherein the second predetermined period that is longer than the firstpredetermined period.